Awesome Ecto Examples

subquery.ex

defmodule MyApp.Projects.Project.Policy do
  alias MyApp.System
  import Ecto.Query, only: [from: 2]

  def scope(%{role: "admin"}, _action, query), do: query
  def scope(user, _action, query), do: projects_for_user(query, user)

  defp projects_for_user(query, user) do
    user_projects =
      from project in query,
        join: delivery in assoc(project, :deliveries),
        join: collaborator in assoc(delivery, :collaborators),
        join: user in System.User, on: user.contact_id == collaborator.id,
        where: user.id == ^user.id,
        select: project.id,
        distinct: :id

    from project in query,
      join: user_project in subquery(user_projects), on: project.id == user_project.id
  end
end